Prediction slurry reactor design under uncertainty using CFD model

Abstract

Mechanically agitated reactors find wide range of applications for solid suspension and mixing in the chemical, biochemical, and mineral processing industries. Understanding the solids dynamics in these reactors is necessary to improve the design and operation of such reactors. Computational fluid dynamic (CFD) models are often useful in this regard, as it can provide significant insights into the flow and mixing of the phases involved. However, the model predictions need extensive evaluation with experimental results before they can be confidently used for the scale-up and optimization of large scale reactors. In the present work the predictive capabilities of CFD techniques as applied to solid-liquid stirred vessels are investigated. Suspensions of sand (diameter equal to 327 m) in water are studied. Eulerian-Granular multiphase model was simulated using FLUNT 6.3.26 to predict the slurry reactor design under uncertainty. The profiles obtained with the Eulerian-Granular approach coupled with the Eulerian, Granular models, and experimental data for comparison purposes. The present model provides an improvement of the predictions in the lower part of the vessel, with respect to the Eulerian model; while the same results can be observed in the rest of the tank where the solid concentration is lower. It seems that the interaction phenomena between the solid and the liquid phases and those among the solid particles do not vary appreciably for low solid concentrations, while at higher concentration some effects become noticeable. It was found that the quasi-steady state behavior of the sand in the mixing tank reached after 20 sec, also after 10 sec were the free surface of the static pressure will be growth until reach peremptory shape after 20 sec. The present model provides a proper representation for the solid distribution, by adopting particle drag coefficient.